The Science

The purpose of this web application is to facilitate knowledge transfer about the energy balance in your body and to provide a tool to help visualize your glycogen store levels. This tool leverages several facts and makes some assumptions to provide the graphs, but none of this should be considered to be completely accurate. With the nature of assumptions, these graphs will show what is the closest to the average person's glycogen levels given the input and is not meant to be exact to the calorie results. That being said, do not do anything reckless like starving yourself to get the numbers on the graph to be lower. This tool is intended to help ensure you are in a caloric deficit and depleting your glycogen stores to lose weight, or to ensure that you are in a caloric surplus and help you gain weight.

Glycogen is the main source of easily convertible energy storage in your body. Glycogen can be found in muscle tissue and organs, including the liver where roughly 25% of your glycogen resides. The other main form of energy storage in your body is lipid storage, aka fat, that can reside intramuscularly, in your organs, and in your adipose tissue. This means as the blood delivers glucose to the rest of your body and either glycogen or fat have to be converted to glucose and be added to the bloodstream to keep a sufficient energy supply to the body. Glycogen is readily mobilized to produce glucose and is used first when providing energy to the rest of the body, so this means that in order to lose fat you need to be in a caloric deficit enough to deplete your glycogen reserves and access your fat reserves (confirm this).

Luckily for those wanting to lose weight, the body needs energy to complete basic functions required to survive, like eating, breathing, moving, thinking, etc., and this can be summed up as your basal metabolic rate (BMR). This means as the day progresses, your glycogen stores drop naturally as you are using energy to climb stairs or do the dishes. This application calculates your BMR with the industry standard Mifflin-St Jeor equation: BMR (kcal / day) = 10 * weight (kg) + 6.25 * height (cm) - 5 * age (y) + s (kcal / day), where s is 5 for males and -161 for females. To replenish your glycogen you have to eat food, and part of the digestion process is the absorption of all the nutrients in the food.

The digestion process is where we first make an assumption. According to the research, your body absorbs all the nutrients and calories while the food is in your small intestine. Additionally, food doesn't reach your small intestine until three hours post consumption and is fully processed after 8 hours post consumption. The first assumption occurs where we assume that all of the calories of each meal you input are absorbed over a five hour period, three hours post meal, and that the absorption follows a normal distribution over the allotted time. This can be visualized in our graph as a spike in glycogen levels after eating a meal.

To combat the increase in glycogen levels, many people exercise daily in an effort to burn more calories than they consume. In this way, we can represent the workout as a drain on your glycogen stores over the duration of the workout. We either ask for an intensity (low, medium, high) and calculate calories burned based on your weight, or ask for the amount of calories burned. Then we model the workout with a normal distribution to subtract energy from your glycogen stores.This is where our second assumption occurs, we assume that we can model the amount of calories burned over the duration of the exercise with a normal distribution.

When we combine BMR, meals, and workouts, we can visualize how much energy we gained or lost throughout the day. This can be useful for maintaining a particular energy level, or analyzing your energy throughout the day to spot significant drops in energy that may be affecting your weight goals. In addition, we have a second graph that displays calories that the glycogen was insufficient to either store or provide, marking how many calories are pulled from storages or added to storages. This can be useful to gather an estimate to manage how many calories you need to gain or lose weight.